Is there any compensation for variation in atmospheric pressure? It is the static atmospheric pressure (psta) that is read by the pressure sensor. I miss-spoke agreeing to it as pressure at sea level. Since the reference is sealed within the sensor, that provides the basis for the sea level measurement.

@Frank - With accurate differential pressure measurement, does temperature need to be taken either side of the orifice ?

This is interesting question. When suppliers provide data regarding the effect of temperature on their sensor it is normally done with both sides of the sensor at the same temperature. If the sensor is temperature compensated, in a flow measurement the temperature sensing is an integral part of the sensor. If a large temperature difference exists between the upstream and downstream measurement, it should be essentially averaged in the sensing circuitry. If you are providing the temperature compensation yourself, what you have to consider is the upstream temperature or downstream temperature more important? Does the situation change over time? The answers may make you consider two temprature sensors but in most cases you should just need one.

@mahdee: I'm not having audio problems today, but I did in the last lectures several weeks ago, and it was because I had updated my flash plugin. I declined an update today. It's possible that others may have updated and are incompatible with the audio stream. I'm running Firefox.

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